1. Field of Invention
The present invention relates to a robot, and more particularly to a robot positioning method and calibration method.
2. Related Art
In the recent decade, robots are generally used in the industry to achieve automatic production. However, most of the applications of the robots are still limited to dealing with repeated processes, and in this case, an experienced operator needs to manipulate a robot in advance to teach the robot to move along a fixed track. In the miniature, diversified, and small-quantity production mode of the electronic industry, the method of teaching the robot by the operator in the automatic production may waste a lot of time, and the manufacturing cost is also increased. Therefore, the prior art provides a method of guiding a robot with a camera device to replace the conventional method of teaching the robot by the operator. However, the method of guiding the robot with the camera device needs to be used together with a stereo vision module, so as to reduce the calibration time of the robot.
In a vision guided robot (VGR) system, the calibration of the camera device and the Hand-Eye calibration are quite important. Thus, it is a critical issue to be solved on how to establish a robot positioning method and calibration method to obtain a transformation matrix of the robot and the object and a distortion error value of the camera device.
Taking U.S. Pat. No. 7,161,321 (referred to as Patent '321 for short hereinafter) as an example, during the calibration of a robot, an acicular object is arranged at a front end of the robot. The robot further has a driving unit, which is used together with a monitoring device disposed on the external side of the robot to perform the calibration of the robot. The monitoring device includes a camera device, a display device, and a control unit, in which the camera device is disposed at a fixed position. The calibration method disclosed in Patent '321 is that, the acicular object on the robot is guided to move to a frame of the camera device, and the camera device captures a frame of a tip of the acicular object. After that, the frame of the tip is transmitted back to the display device, the control unit calculates a transformation matrix between the robot and the display device, and the control unit drives the robot to move to the position of the display device.
However, the monitoring device in Patent '321 is an apparatus configured at the external side of the robot, and the monitoring device needs to be additionally purchased when buying the robot. Thereby, the technology disclosed in Patent '321 has a high apparatus cost. Further, in Patent '321, every time before the calibration of the robot, the monitoring device configured at the external side of the robot needs to be electrically connected to the robot, so that an additional time is required before the calibration to electrically connect the monitoring device to the robot, which increases the calibration procedure of the robot, and reduces the calibration efficiency of the robot. In addition, during the calibration of the robot, the camera device captures the frame of the tip of the acicular object, and transmits the frame back to the monitoring device configured at the external side of the robot; then, the monitoring device calculates a transformation matrix between the robot and the object, and guides the robot to move to the position of the display device according to the transformation matrix, such that it is impossible to transmit the transformation matrix back to the robot in time, and thus the calibration method in Patent '321 takes an excessively long calibration time. Therefore, in Patent '321, too much time is wasted before calibration, the apparatus cost is high, and the calibration time is too long.